Telephone system.



H. 1; scams, TELEPHONE SYSTEM.

APPLICATION FILED NINE 8. "0|.

Patent/ed Mar. 11,1919.

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Hr). ROBERTS. TELEPHONE svsnu.

APPLICATION fllfll NINE 3. "0|.

1,297,251. Patented Mar. 11,1919.

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H. l. ROBERTS:

TELEPHONE SYSTEM. A'm-ucmou FILED war 2. won.

1,297,251 Patented Mar. 11.1919.

13 sunns-sntn l. ROBERTS.

TELEPHONE SYSTEM.

umcmou FILED JUNE a. 190x.

Patented Mar. 11, 1919.

I3 BNEETS-SHEET il. ROBERTS.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE 3. won.

Patented Mar. 11. 1919.

I! SHEETS-SHEET H. 1.ROBERTS. TELEPHONE SYSTEM.

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Patented Mar. 11.1919. 9 1a suns-sneer a.

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wt ifne H. I. ROBERTS. TELEPHONE SYSTEM.

nrucmon HLED was a. 1901.

Patented Mari 11. 1919.

02672 eye 6,5 1m? 2602*.- acaw. Q mww/ Aimefi H. J. ROBERTS.

TELEPHONE SYSTEM.

mwucmou mw JUNE a. mu.

Patented Mar. 11, lSHQ.

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H. J. ROBERTS.

TELEPHONE SYSTEM.

APPLICAIION min was a. 1901.

1,297,251. Patented Mar. 11.1919.

1; SHEETS-SHUT l2.

HIIKIIHI H. J. ROBERTS.

TELEPHONE svsmn.

APPLICATION HLEO 1M3. 190i. 1,297,251. Patented Mar. 11. mm.

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6 www HOMER J. ROBERTS, 01' EVANSTON,

ILLINOIS, ASSIGNOR. BY MESNE ASSIGNMENTS. TO

AUTOMATIC ELECTRIC COMPANY. A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Ma r. 1 1, 1919.

Application tiled June 3. 1991. Serial No. 62,941.

To (all who)", it 771(11/ concern:

Be it known that. I, Hoiunn J. Rouan'rs, of Evanston, Cook county. Illinois, have invented certain new and useful Improve ments in Telephone Systems, of which the following is a specification.

y invention relates to telephone systems in general, but more particularly to telephone exchange systems in which provision is made for trunkin between exchanges. or between different divisions of the same exchange, and especially to systems in which current is supplied to the subscribers lincs from a central source. for operating purposes, as well as for talking purposes.

Generally stated the object of my invention is to provide a telephone exchange system in which provision is made for extending the calls with rapidity and certainty, and in which the cost of installation and the expense of maintcnance are low, and the efficiency high, considering the methods can ployed.

Special objects are to provide means by which a calling subscriber may automatically connect his line with an idle trunkline leading to a manual switchboard; to provide two-way trunks, and means for antomatically seizing either end thereof, for the purpose of trunking between exchanges, or between different divisions of the some exchange; to provide an improved automatic trunk selector for selecting idle trunks; to

provide an arrangement by which a calling subscriber may automatically connect his line with either a local trunk or a long-distance trunk, depending upon whether he is calling a subscriber of his own exchange or division, or a subscriber of some other oxrhaing"v or division; to provide twtrway trunks and means for automatically seizing either end thereof, together with means for automatically precluding the seizure of either end of a trunk by other subscribers, whereby the subscriber already in possession of such two-way trunk is protected against interference by said other subscribers; to provide two-way trunks and means for automatically seizing either end thereof, together with means for manually connecting with either end of the same, whereby connection can be extruded automatically to one end of a trunk. and connection from the other end thereof to the called line then completed manually; to provide a novel ar- 'less in number than the, subs ribers having lines terminating at such board, the. sai

signals being common to all of the subscribers. and where y the manual switchboard operator may determine which line is calling before answering the call; to provide means by which a manual switchboard o crater may release a calling subscriber tom a trunk to which the said subscriber automatically extended his line in making the call, and whereby the said operator may do r0 either bcforc or after answering the call, and either before or after the called subscribe-r answers: to provide an arrangenu-nt whereby the calling subscriber can push one button or equivalent device and thcr bv automatically extend his line into connect ion with a trunk-line at his own exchange, or push another button and thereby auwmatb cnlly extend his line into connection with a trunk-lino leading to another exchange, there being as many push-buttons or equiva lent devices as there are exchai'iges or divisions of the same exchange; and to pro vide certain details and features of improvement and combinations tondin to increase the general ctiicicncy and serviccability of n. telephone. exchange system.

To the foregoing and other useful ends, my invention consists in matters hereinafter set forth and claimed.

In the accompan ing drawings Figure 1 is a plan view (with parts broken out to reduce the size of the figure) of a trunk selector embodying the principles of my invention.

Fig. 2 is a view showing one of the selector bars and principal operating parts in side elevation, a fragment of the side casing 1) opposite the pair of ma nets D being shown in side elevation, and tie remainder of the casing heing shown in longitudinal vertical section.

Fig. -'-i is a fragm ntary detail of one. of tho circuit-opening devices shown in Figs. 1 and 2.

Fig. 4 is an end elevation of one of the trunk selector elements (and the magnet which operates the same) looking at the end of the element opposite that shown m Fig. 2.

Fig. 5 is a fragmentary plan view of two adjacent. selector-liars. contact devices car ried thereby, and the suhjacent trunk elements with which said contact devices cooperate.

Fig. 6 is a detail side elevation of the com tact device shown in Fig. 5.

Fig. 7 is a plan \ien' ol a mechanical detent wherel\ th .o'h'ltnP-bfll' is temporarily held at the end of its initial movement.

l' ll m uni t" loin-n together constitut a tiiopranooatu no of a telephone system embodying llw pilllitdcs of my invention.

l'dg. i is a l'llilnlilli'littll (If Fig. 2 Willi the several imulul ing: parts properly shaded t0 indica ith ir character.

Fig. ll is a plan view on an enlarged scale oi the lcftluznd end of the selector instrument. shown in Fig. I.

Fig, l] is an a d elevation of the same.

Fig. 12 is a, trai'isrcrsc. sectional view taken in a vertical plane lad ween two of the trunk elements aul looking toward the left-hand end of the instrument.

Fig. 13 is a perspective view of one of the trunk elements in enlarged detail.

Fig. 14 is a cross-section of Fig. 13.

Figs. l5, l6 and 17 taken together are a detail diagrammatic representation of the whole system.

Fig. 18 is a simplified diagram of the entire telephone system.

Fig. 19 is adiagrammatic view showing the circuits and other means whereby an operator can identify a calling suhseriher after he has signaled the operator.

Fig. 20 is a simplified diagram representing the pomplete talking circuit between two connected substations in a system embodying the principles of my invention.

In carrying out my invention a plurality of exchange stations are connected by trunks which severally terminate at. each end in an instrument or apparatus capahle of operation by any one of a series of suhscrila'rs of the exchange in which the instrument in located, and said instrument operating to auto matically select one of the trunks terminating thereat. wherehy the urn-rating snhscrihcr is placed in direct communication with the exchange operator at the other end of the trunk. Automatic means are provided whcrehy the act of selecting a trunk gives to the suhscrila-r for the time heiugz the exclusive use of this trunk and prevents interference by other subscribers belonging to the same or any other exchange. 'l'here fore, the system embodies means wherehy all of the trunks extending hetueeu a Hill]- scrihers local exchange and any and all other exchanges are equally avaih xble to him when not in use. In other words, the said trunks are common. the operation of selceb ing one of these trunks giving him the exclusive use of the trunk for the time being.

Having thus outlined the general plan of the system, the main instrument whereby the automatic selection of the trunk-lines is accomplished will first be described indetail. and thereafter the interconnections or system as a whole, and in this connection it may he stated that in its broader sense the scope of the invention is not confined to the use of the particular instrument herein described. hut. on the contrary. any suitable apparatm may he. employed for effecting the several connections and operations.

Referring to Figs. 6, 8', l3. 15, 1G and 18. A designates as a whole a series of oscillatory trunk elements pivotally mounted to extend parallel ith each other across a suit able frame I! (Figs; 1. 11 and 12); and i (Figs. 1. 2. 9. I0. 16 and it'll designates a series of subscribers selector-fliars arranged to extend parallel with each other and transrersely of the trunk elements A.

In the drawings (Figs. 1, 2, 9 and 10) hot too of the trunk elements A are shown. hit. in practice as many trunk elements will he provided as there are trunk-lines. and they will be grouped together electrically in as many groups as there are exchanges interconnectml. (See Figs. 8. 8. 15, 16 and 18.)

As a convenient construction the trunk elements A are of bar-like construction. made of insulating material and provided at each end. near the lower edges. with trunnions 0 (Figs. 11 and 12) on the main frame. whereby they are pirotally supported so as to he ca pahle of oscillation through a limited range of movement. The trunk metnlxws are adapted to he. oscillated forwardly in two distinct and successive steps. (lH'll'l uagnets as indicated respectively at I) (Fig. I), located at. the ends of said elements. heing employed for this purpose. The. magnet which is the first in order of operation. comprises the usual spool c (Figs. ll and 12) arranged to actv upon an armature a (Fig- 4) mounted upon an arm 1- pivotally secured upon the trunnion 0 (Fig. lit) of the trunk element. In ordcr that the armature may itself oscillate the trunk element forwardly a certain distance. and thereafter permit the trunk element to he oscillated a second step by the magnet I at the opposite end thereof, a stop 1'" is provided upon the trunk element in position to he engaged by the under side of the arm c when the trunk element is in its normal or retracted position and tho armature hcld retracted from the magnet.

The magnets l) at the opposite. ends of the trunk i-lcmcuts are similar to the magnet. l, cmnpuisih the usual spool 11 (Figs. 2, 11 and 12) mounted upon the frame and arranged to a t upon the armature 1i mounted upon an arm 1]" which is rigidly secured upon the trunnion :1 of the adjiwent end oi; the trunk element. The arm J is: secured upon the trunion a in such angular relation thereto that when the trunk element has been rotated fOiWWLl'tll) the first step by the magnet (l at. the opposite end thereof, the armature (1' will. he brought into position to he etlectively attracted by the magnet I) for imparting the second forward step to the trunk element, at which time the armature a" is drawn down into engagement with the core of the magnet. D. Both the magnets C and I) operate to open and close electrical contacts, as will hereinafter be more fully described. The arm d carries also upon its upper side a pivoted arm cl of insnlating material and provided upon both its upper and lower sides with contact strips 11" and d respectively. See Fi 8*.) A back contact. device n" Fig. 12 normally forms both an electrical contact with the strip and a mechanical back stolp for the armature arm.

pon each trunk element A is mounted a. series of contnct studs (see detail Fig. 13), soverall y designated a, these studs being an ranged in longitudinal alincment with each other and in position to register with each of the individual selector-bars E. The several studs a constitutecontlact devices adapted for engagement with corresponding oontact fingers e (Figs. 2, 8', 9 and 10-) mount:

ed upon the selectorhars E, these contact fingers e servin not only to form an eloctrical contact with the trunk elements, but also as tap 5 whereby the selector-bars are thrust orward by the forward oscillation of the trunk elements. as will hereinafter appear.

In the operation of the instrument the sclcctor-bar is moved bodily endwise forwardly a certain distance before the trunk element is oscillated, this distance being such as to bring the engaging ends e (Figs. 2, 9 and 10) of the several contact fingers vertically above the trunk elements and slightly in advance of the several contact devices (1. carried thereby. The location of the contact fingers relatively to the path of movement of the contact studs 11. is such that after being thus advanced to a position directly above the trunk elements their engaging ends will lie in the path of the contact studs, so that when the trunk clement is oscillated forwardly one of the contact studs which is opposite whichever one of the selector-bars that happens to be moved forward will en- ;zugc'its corresponding contact finger and thrust it. forward during the two advance steps of the trunk clcmcntafterward affected by magnets and D. The first step of the. trunk i-lcmcut. curries its contact devices a into a position approximately vertically nhovc its axis, while the. second step carries 'itv into a )OHlLiOll beyond the perpendicular.

so that w ten the trunk clement is in its normal retracted position, and when it is advunced to its forward limit, its contact studs are below the path of movement of the contact fin as e, as the latter move horizonl'all orward when the selector-bar is shi ted bodily. The object of this arrangement is to prevent interference with the particular trunk element in operation by the movement of other selector-bars while thus in selected position in any given operation. In order that the contact. fingers 6 may retain contact, with the studs a after they have been thus onceengaged, said fingers are pivotnully mounted upon the selector-bars. as indicated at. 6 (Figs. '2, (i and 9), and are provided with rigidly attached upstanding plate springs e having their studs confined ietween guide studs 1' which serve to hold the several contact. fingers in exact position to register with the contact studs, as described, while permitting the contact fingers to oscillate downwardly after engagement with the contact studs. In order to prevent. such contact fingers from slipping out of engagement with the contact studs, the latter re made of under-cut form at their engaging sides, as best indicated in detail Fig 6. At the same time that the electrical contact is closed between the several contact fingers and studs a, two other circuits are closed between the trunk element and selector-bar, and for this purpose each contact finger e carries at each side a contact strip e and c" (Fig. 5) respectively, secured rigidly thereto and arranged to project. at. their free ends at each side of the engaging end of the finger and in position to engage with contact plates -or surfaces 0' and a (Figs. 5, (i. 13 and H) located at-the respective Hides of the contact studs 0.. The shape of the contact strips c and e is such that when the engaging and of the contact finger is engaged with the stud u, the toggle-like movement of the contact. finger relatively to the trunk element will rock the ends of said contact strips into certain engagement with the respective contact. plates or surfaces upon the trunk clement, thus in- Hllllng the closing of the three circuits. As licrcinhcforc intimated. the selector-burs are. thrust forward PHYlUHsNI their engagement by the trunk clcnu-nts. .\s a convenient means of imparting the initial forward movement to the selector-Inn's. I provide a pair of transversely-cxtcnding pivotullysupported bars designated respectively F and (i (l iga .3, 3, 8, J and 10), each of said bars being at a length suliicient to extend entirely across the series of selector-bars, said bars l" and (i being severally mounted upon upstanding arms f and g (I igs. 2, 8, 9 and H) located at the respective ends of the bars F and (i. which arms f and q are pi votally iiioulited at their lower ends upon the main frame, as indicated at f and g. H designates a magnet suspended from a crossbar 11' (Figs. 9 and 11) of the main frame in position to overhaii an arm I rigidly connected with one of t ie arms f of the bar I and arrying an armature h adapted to be acted upon by the magnet H, the liftin of the arm 1' by the magnet serving to oaci late the :H'Hih forwardly. and with them the (l'HSt-i-lltll' supported at their upper ends. I t Fig. lidesiguatea a sei'iesot' thrust-levers, one for each selector-bar, adapted .l'or engagement by the thruwtbara l" and (1 to force the seleeto|--bar forwardly. Each thrust-lever l l\ imted at its forward end, as indicated at i. to the body of the selectorlinr, so as to be capable of oscillating in a vertical plane parallel with the plane of said selector-liar. and is normally held uplifted and in engagement with a stop i by means of a suitable. spring, as indicated at F. At its rear end the thrust-lever I is provided with two contactdevices i and i respeetirely. adapted for engagement with the respeetive thrustdiara l" and (i. In the normal position of the parts the contact device i" is located directly above an engaging notch or shoulder f (Fig. 2) so formed in the. up ier part of the bar that when the thrust-lever is drawn downwardly. as hereinafter described. the contact device i and said notch will be brought into operative engagement and electrical contact to thrust the selector-bar forward by the subsequent energizing of the magnet H and consequent,

thruatint forward of the bar I". In order to than draw down the thrust-lover a mag; net J is mounted upon the selector-bar immediately beneath said thrust-lever, and an armature I is mounted upon the thrust lever in )osition to be attracted by the, magnet J. referably, in order to economize inspaee, the magnet J will he made of flattened form and set within a recess formed in the body of the se ector-bar, as indicated in the several figuret of the drawings. The drawing down of the thrust-lever closes a circuit through the magnet ll which thereupon thrusts forward the selector-bar a. certain distauce'agaiust the tension of a coiled expansion airing K interposed between the forward em frame iiiembor b and the front.

end of the selector-bar. In order to hold the. SOlO-(PlUV-btll temporarily in this position, aml against the tension of the aprin after the magnet II has been dee'inrgized,

a mechanical detcut is provided comprising a pivoted dotent 1 (Figs. 2 and T) mounted upon an upetandin plate-like support L arranged to extent vertically adjacent to the side of the aelector-bar, which detent is adapted to engage a notched latch member I pivotally mounted upon the upper edge of the selector-bar, so as to be capable of lifting upwardly and permitting the engaging end of the detent to slide under it upon the return movement, of the bar, as hereinafter to be described. The engaging end of the detent l is in the form of a rigl'it-a-ngled projection I (see detail Fig. '7) which, when the selector-har is in its normal position, registers with the lies within an opening formed through the latch member I. The engaging notch Z of the latch member is located in rear of the opening I, that part of the latch between the opening and the notch being in the form of a rearward]; and upwardly extending inclined portion covered with insulation. From the engaging face or shoulder l of the. latch the rear end ortion ot' the latch i also inclined upwartlly, and is located a sutlicient distance above the upper edge of the selector-bar to enable the angular portion Z of the detent to pose under the latch member cam fashion, and Lift the latch upon the return movement of the selm-tor-liar. The first forward step of the selector-bar, under the action of the ba r 1, carries it. into position for the detent l to engage the notch l. The secondti'onward ate is imparted to the selected-bar by means of the thrust-bar (l which is provided with an arm carrying an armature g and acted upon by a magnet M (Fig. 2) constructed and arranged substantially like the magnet ll and supported from a cross-bar b". The upper portion of the thrust-bar G is provided with a shoulder or notched portion y, adapted for engagement with the contact device if of the thrust-lever in substantially the same manner as described in connection with the thrust-bar F. The contact device 1: is shorter than the contact device i whereby, when the contact device i enga s the thrust-bar F, the contact device 1" wt l clear the top of the thrustdiar- G. However, after the thrust-bar F returns to normal position, the thrust-lever I having been advanced to a position with the contact. device i just above the engaging notch g, the magnet. J, upon energizin a second time, may then attract the thrustever 1 so as to cause the contact i to cngagetlie thrust-bar G. It will be evident, however, that this particular construction ll$ not absolutely necessary. It is obvious that. the contact device i n'iav he in the nature of a ratchet, in which ease ioth contacts 11' and i may be of the.

same length. The part i will then give way each time itengages the edge of thethrustcourse. in that event it will be necessary, however. to insulate either the curved portion of the contact d vice a" that engages the thrust-bar (l or the front part of the thrustbar (i. The two forward steps of the so lvctor-bar bring the engaging ends of its several contact lingers rinto positions substantially vertically above the axes of the scwt'al trunk elements, and in position to be engaged by the contact studs a thereof, as hcminbet'orc described. Al. the end of the forward movement of each of the thrustbars I and G a switch operates to open the electric circuit extending through magnets H and M, and as a convenient. construction for accomplishing this end, and at the same time provulin a switch which will not re establish the circuit until the thrust-bar has completely returned to its normal position, I provide a construction as follows 5 f (Figs. 3 and 10) designates a contact block mountcd upon the frame member 6 at a oint in rear of the t-hrust-ba F, and Jrovided on one of its side faces with an oli uely upward and forwardly-extending guide-groove f". (See detail Big. 3). f designates a spring contact strip secured to the thrust-bar 1* and extending backwardly therefrom and provided at its end with an angular portion or stud f adapted to engage the groove f". The spring strip f is so shaped as to tend to assume a horizontal position intersecting the central portion of the loath of the groove. so that when the thrustar F is in its normal backward position the spring strip will be flexed downwardly by engagement with the guide-groove, and will tend to spring upwardly, and vice versa, when the thrust-bar F approaches its forward limit of movement the guide-groove will force the spring strip upwardly so that it will tend to spring downwardly when it passes out of the groove at the end of such forward movement. That portion f which forms the lower side of the guide-groove is in-nlatcd upon its under surface, as indicated atf, (see detail Fig. 3) and is inclined or made shoe-shape at its front. ended as to direct the engaging end I of thcspring stri i downwardly beneath the said portion upon the return movement of the thrust-bar,

while at the rear end of the portion f a slot f is provided through which the engaging end of the spring strip may pass upwardly into the slot f". A similar switch device, designated as a whole g" (Figs. 2 and 10). has its respective parts mounted upon the frame member I) and the thrust-ha r (i, and operates in substantially the same manner-to open and close a circuit when the thrust-par G is operated.

N and N, rea 'iectivcly, (Figs. 2 and designate a pair of longitudinal rceipro eating contact devices moun'wl upon the forward end of the selector-bar and adapted to engage at their forward ends with contact plates n and n, respectively, when the selector-bar is moved forward. The contact devices N and N are maintained in their normal forward positions by means of coiled expansion springs n int/imposed between fixed guides n" and n, which guides are rigidly connected to the selectorbar. The contact devices are ada ted to slide through the collars n and n, at the collars n being rigid with the respective contact devices N and N serve as stops by engaging the collars n to limit the forward movement of the contact devices under the influence of their springs, thereby holding said, contact devices free from engagement with the contact plates n and n when the selector-bar is in its normal or rearmost position. The several selector-bars am supported to slide endwise by resting at their forward ends upon a, supporting ledge b, and at their rear ends a on the upper edge of the crossbar 6', said bars being spaced apart at their forward ends by means of upper and lower space-blocks b andb', while at their rear ends theyvare similarly guided by resting witliiii notchs formed in the upper edge of said member 6'. (See Fig. 11). At the end of the forward movement of each selector-bar it is necessary that two electrical circuit-s be opened, and, as a convenient means of accomplishing this ';cnd, I provide upon the selector-bar a, pair; of spring-closed contact devices res actively;

designated as a whole 0 and O ig. 2), said contact devices being located in osition to he opened b the cnga ementt ero- -with of the rear on s of the slit ing; plungerlike contact devices N and N. Conveniently, each contact device comprises a fixed member 0 against which is forced a movable member 0' mounted upon a V-shaped 5 ring 0 which is rigidly secured to the si e of the selector-lair by means of a stud a. The nun-able contact device 0 is located in alinemeat with the and n of the sliding contact device, the engaging end portion of the latter being of insulating material so as to prevent interference with the circuits of the contact devices engaged thereby. It is also necessary that a certain other circuit he opened and closed during the movement of the selector-bar, and to this end I rovide a s )ring contact designatpd as a w ole whic is mounted upon the fixed stand' and L (Fig. 2) and is adapted to be engaged by a latcrallwpriijecting stud a mounted upon and carried by the selectorhar. Said contact device 0 embraces a Vshapcd spring rigidly secured to the standard he means of a s1 ad a and normally resting-in engagement at its free end with a fixed contact 0. The projecting end portion a" of the contact )ring is adapted to he engaged by the Htllt o" and forced back when thoselector-Inn approaches the limit of its second forward step under action of magnet M to open the circuit of magnet J. A spring contact device 30" mounted upon the support L' is also rovided which is adapted to be engagetr by a Contact p" mounted u on the top edge of the selrrtonbar for t e uriose hereinafter described. The main Ines and L terminate in the selector instrument at a bar E individual to the line, but the operating circuits by'which the selector instrument is operated are controlled by a. cut-oil relay 1. The object of the said'rolay l is to automatically cut oil the opcrating circuits from a subscribers line when the said subscriber is called, and to provide a busy-test at all test. rings allotted to the line called. T0 briefly describe this part of the system P desi nates the relay coil, P, the armature, whici is in the usual form of an angular metal plate pivotally supported at its angle and operating when attracted by the magnet l" to simultaneously lift three contact strips p, 7'1 and p, respectively, the contact strihs p and I) normally resting in contact with lower fixed contacts 12' and p, respectively. .The main lines R and L leading from the subscribers instrument are respectively connected with the contact strips p, and and are thus normally closed with com actors p and p both of which lead to and through the selector instrument. The contacts p, p" and p. are the three upper contacts which, when the relay energizes, are enguged by springs 12, p and p. The contacts p and p are, as shown, connected through conductors p" and p with conductors p" and p" common to the several connoetin jacks designated as a whole I" and l". he up er contact p of the relay is connected wit ground through a conductor p, while the cooperatm lower contact strip p'js connected throng a conductor p with a conductor p" common to the blunch conductors leading to the several test rings 9". he conductor p", which is connected with the test circuit, is likewise connected three a conductor 9" with a contact 11*." whici is engaged by a cooperating contact 1) carried b lertor-bar whenever said bar is shifted forwardly. The insertion of the operators plug in any one of the cimnec-ting packs 1, etc, closes a local circuit from a conductor 11'" thmugh the contacts p" and p of the jacks. from the latter contact through a conductor p to a conductor p" common to each of the jacks, and from this latter con-- (luctor through a conductor p" to and through the -rela and back by way of a conductor p" to attary P, the end of conthe sedin-tor 1)" being connected with the opposite side of the battery b a conductor a", as elearl shown in the (in am.

Descri ing now the severe circuits from the subscriber's set through the selector, it will be remembered that the first operation of the selector is to draw down the thrust lover I to close a circuit which energizes the magnet H and thrusts forward the selectorbar to a position where it is on; and held temporarily by the mechanics detent. Pointing out the circuit through the magnet J which operates to draw down the thrustlever (see Figs. 8 and 8 it extends from the grounded terminal of attery P through conductor 0', thrust-lover I, conductor e to the contact a, conductor 1), throu h the cut-oil relay springs p and pto t e left line L, thence through the subscribers station passing through the receiver and transmittcr thereof to the right line it, to the con tact spring 71' of the cut-otl' relay P, thence to the contact 1), conductor p to the fixed contact 0 mounted upon the standard L, as hereinbefore described. thence to the spring contact 0 normally resting in engagement with the fixed contact 0, corn doctor 0'', and throu h the magnet J, thence by Way of the C0! uctor o" to the nongrounded terminal of battery P. The energizin r of said magnet J draws down the thrust ever and closes a circuit throu h the magnet H which may be traced as fo lows: from the thrust-leverI which, as hereinbefore described, is in connection through the conductor 0 with one side of the battery, current passing to the thrust-bar F and from the latter through contact strip f to the contact f, thence by conduct-or f" to' and through the magnet H, and b conductor f" to conductor a" which, as ereinbefore described, is connected with the opposite side of the battery, thus completing the circuit. -Thc energizing of the magnet H thrusts forward the selector-bar to a position where the latter is engaged by the mechanical detent l and simultaneously opensthe circuit between the contact strip f carried by the thrust-bar and fixed contact f. The inclined part I of the latch Z (See detail Fig. 7) of the mechanical detent is covered with insulating material which prevents the closing of a circuit between the latch-member and (latent member until the latter dropsinto the notch 1 thereof. The dropping of the dotont in to the note 1 serves to close at this point a second circuit t rough the magnet J, which circuit, however, is not completed until the sulmriher completes it by ressing one of his signal buttons or or 3 w icli ground the line L. The completion of the circuit by pl'essiu r either of said signal buttons a: cry draws (own the thrust-lever a second time, and thereby closes u circuit which energizes magnet M, which magnetM operatesto move the selector-bar forward a second ste i in sub stantially the same manner described in connection with magnet H. The second circuit through the magnet J may be traced as follows: from ground at the suhscrihcrs station to the left main line, to a conductor which is connected at is opposite end with a conductor strip 0' mountci'l upon the upper edge of the selector-bar, and with which the latch member I is electrically connected, from the latch member to the detent, and thence through the conductor q to and through the magnet J, thence by way of conductor 0" to battery, and from battery to ground through a conductor 0. When, however, one of the signal buttons to or z: is operated a different circuit is closed through the magnet J which may be traced as follows: from ground at the subscribers station to the right-hand main line to and through contacts 7) and p of the relay 1, thence by way of conductor p" through contact device contact a", conductor a" to the magnet, thence by conductor 0 from magnet. to battery, and mm battery to ground, as before. Inasmuch as the second orward movement of the selector-bar under the action of the magnet M opens the circuit at the switch g which energizes said magnet M, it is necessary to provide aretaining circuit through the magnet M to maintain the latter energized after the circuit therethrough is opened at switch g". This circuit is hereinafter described. The pulling down i of the thrust-lever this second time closes a circuit from the thrust-lever through contact contact 9', to conductor 9' and to ma met M. From the magnet M a conductor q ends to conductor a", and through the latter to batberg; From the battery the return circuit is y Way of conductor a to the thrust lever, as in the case of the circuit through the magnet H. The second forward stc]: of the selector-bar closes the circuit between and N and the contacts a and a, whereby the trunk-selecting operations are performed at the same time, brings its several contact fingers e in position for engagement by the trunk elements, and closes a circuit which selects one of the trunk elements of the particular exchan e desired (depending upon which signal Jutton the subscriber has operated) and operates the exchange system. As shown, the subscribers set is capable of sending outfour dili'crent kinds of signals, since the number of exchanges interconnected in this particular case is four, each signal corresponding to a dili'cl'cnt exchange. The four ditl'crcnt. kinds of signals employed in the present. instance omprise two sent over the right and left lines, respectircly. without resistance, and two sent over the right and left lines with resistance interposed in each, thus giving the four signals of ditl'crcnt. character necessary to o erate the relays responding to such signals. In Figs. 8, 8' and 15 the arrangement of the subscribers set is shown diagrammatically by which the four different signals or impulses are accomplished. In said res, R and L designate the right and le main lines. respectively. r the transmitter, r the recei er or car telephone, and r the switch lcvcr which ser es as a hook upon which the ear telephone is ordinarily hung when not in use. 1" designates a conductor provided with a plurality of contact devices 1", 7"", r and 1" adapted to he severally engaged 11 moving contacts r, r, r and r opcrablia respectively by four signal buttons :0, 11 w and 2 which severally mrrespond to the magnets X, Y. W and Z of the selector system. One end of the conductor 7* is placed to round at the subscribefis station, as indicated in the diagram. .The 0 eration of signal hutton 11' operates to sew: an impulse through the right main line to a directing rclnv S with out inter m-ted resistance and lo thus operate a magnet W, as hereinafter described, the circuit through the hutton being traced as follows: Upon depressing the button 10 the contact 1"" )8 brought into circuit with contact device 1", and the circuit is then from ground at the subscriber's station through conductor 1', through contacts 1' and r through a conductor 1"" connected with the contact 1' and thence to the right main line and to the selector. After reaching the sch-clot it will he seen that the impulse passes from the line It to the conductor a, thence to the conductor e", through the contact device (Y to the conductor N, thence 'to the contact a through the relay S, and through the magnet W, thence to the. non-grounded terminal of battery I, passing first throu h the relay V (Fig. 8). Since the impu se is transmitted to these relays h and \V without any interposed resistance at the telephouo, hoth o1 thc relays will operate, but the relay S operates with no result of. consequence at this time. It will he understood, of course, that the impulse cannot reach the magnets S and 7 until after the magnet M has operated to close the circuit at the point between the conductor N and the contact. n. The depression of the signal button to operates to open amnurct r to separate the ri ht line from the left line through the to cphone instrument and by way of conductor r. If the signalhutton z is depressed an impulse is first sent over the right line-with resistance included, thereby opcratillg the magnet Set the selector system, the circuit being traced as follows: from round at the subscriber's station throng l conductor 2' to and through a resist- 

